1. Field of the Invention
The present invention relates to the reduction of ambient noise during a voice conversation using a mobile terminal. More particularly, the present invention relates to a second microphone device of a mobile terminal that enhances the reduction of ambient noise.
2. Description of the Related Art
As mobile terminals become more sophisticated, users expect additional features as well as a high level of call quality. To address the issue of call quality, technologies that include a second microphone for removal of ambient noise are often applied to mobile terminals.
FIG. 1 is a perspective view of a mobile terminal having a second microphone device according to the related art, and FIG. 2 is a perspective view of the mobile terminal of FIG. 1 from a different angle according to the related art.
Referring to FIG. 1 and FIG. 2, a main microphone 102 receives the voice of a user, transforms the received voice to an electrical signal, and transfers the electrical signal. The main microphone 102 is generally installed on the bottom of a mobile terminal 101. A second microphone device 100 is located on the mobile terminal to assist in achieving optimum performance by removing ambient noise other than the user's voice. Therefore, as shown in FIG. 2, the second microphone device 100 is installed on the top of the mobile terminal 101 in a direction opposite to the bottom of the mobile terminal 101 where the main microphone 102 is installed. However, the second microphone device 100 may not be installed on the top of the mobile terminal 101 in some cases, due to an undesirable appearance of the terminal caused by a microphone hole 120 exposed to the outside of the mobile terminal 101 and due to limitations of mounting conditions of the mobile terminal 101. For example, the top of the mobile terminal 101 already includes an ear jack connector 110 for use in connection of an earpiece so that an additional hole for the second microphone 100 is even more unsightly and would require additional processing costs when creating the additional hole.
Accordingly, a second microphone device of a mobile terminal may be embodied in some cases by using a receiver hole 103, which is provided for a speaker that outputs a voice of a corresponding person to the user, or at a rear or side of the mobile terminal. However, in any of these cases, because an object such as an ear, a hand or the face of the user closely contacts a second microphone hole installed in the receiver hole 103 or at the rear or side of the mobile terminal, there may be a problem that ambient noise may not be received by the second microphone device of the mobile terminal, thereby decreasing an ambient noise removal performance.